Today's cellular phone networks use various procedures to enable a user to use multiple end devices (the so-called twin-card and multi-card products). This type of product configuration may result, for example, from the parallel use of mobile end devices, a car telephone and an organizer. In this scenario, one or several end devices are activated at the same time for outgoing and incoming calls under a uniform number. In configurations with several simultaneously active end devices, any incoming connection requests occurring under a uniform number are signaled in a parallel manner to the various end devices of the subscriber.
The disadvantage of the existing procedures for such parallel call delivery results from the uncertainty of the status of the end devices (switched off, technically not reachable, busy). This uncertainty may cause:                Unnecessary occupancy of cellular and land-based network resources for attempts to connect that are actually unnecessary        Network services such as call forwarding to be executed in the network area of the end device being called, which may lead to partially undesired product scenarios and, in particular, to the unnecessary use of network resources, and to substantial additional costs for net operators and end customers.        Network services, such as call forwarding, depend on data records that are separately assigned to each end device within the network. Since these data records are not automatically synchronized, the result is a different call behaviour depending on which particular end device is being used and/or a substantial cost for the user to manually synchronize the end device data records. Furthermore, the user's selection options for the settings of the network services must be restricted in order to guarantee the correct network behaviour during the delivery of parallel calls.        
EP 0 711 090 A2 discloses a method to control a configuration of telecommunication end devices comprising an arrangement of two or more end devices (multiple-device configuration) in a public telecommunication network. A number of subscriber identification chips share one single subscriber identification number.
U.S. Pat. No. 5,708,809 A describes a method to update the program structure of a modular communication facility, which consists of several modules connected to each other through a bus. Upon the commencement of operation or a change in the configuration, the program structure is automatically updated separately in each module.
EP 0 740 482 A1 relates to a telephone management system in the form of a separate processor set up with the subscriber, which enables the connection of a number of subscriber's end devices, such as cellular phone, cordless telephone, answering machine, etc. When an incoming call arrives, the processor forwards it to the momentarily “active” and device.
WO 01 0708 A1 discloses an automatic call distribution system similar to the one of EP 0 740 482 A1 with the difference that, here, the distribution of calls to connected end devices is performed by a network element of the communication network.
Therefore, the technical task of the present invention is to propose a method and a system configuration that will guarantee a network resource-saving control of end devices arrayed in a multiple-device configuration and, at the same time, to provide the user with a central control for all system behaviour.
This technical task is resolved by using a special control circuit and the associated process according to the characteristics of the invention claims, the disclosure of which we herewith make reference.